Circuit for resolving I/O port address conflicts

United States Patent [i9]

Hwang

[54] CIRCUIT FOR RESOLVING VO PORT ADDRESS CONFLICTS

[75] Inventor: Shih-Tsung Hwang, San Jose, Calif.

[73] Assignee: Advanced System Products, Inc., San Jose, Calif.

[21] Appl. No.: 111,191

[22] Filed: Aug. 27,1993

[51] Int. CI.6 G06F 13/00

[52] U.S. CI 395/829; 340/825.07; 340/825.52;

395/834; 395/835; 395/836; 395/284; 364/DIG. 1;

364/238.3; 364/280.2

[58] Field of Search 340/825.07, 825.52;

364/DIG. 1, DIG. 2; 395/200, 275, 325, 400, 800, 200.1, 828, 829, 830, 834, 835, 836, 284, 490, 497.1, 700

[56] References Cited

U.S. PATENT DOCUMENTS

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4,633,392 12/1986 Vincent et al 395/325

4,660,141 4/1987 Ceccon et al 395/275

4,675,813 6/1987 Locke 395/829

4,730,251 3/1988 Aakreetal 395/325

4,773,005 9/1988 Sullivan 395/275

4,775,931 10/1988 Dickie et al 395/829

4,899,274 2/1990 Hansen et al 395/200

5,014,193 5/1991 Garner et al 395/830

5,038,320 8/1991 Heath et al 395/275

5,274,771 12/1993 Hamilton et al 395/275

5,301,276 4/1994 Kimura 395/275

illlllllllli^

US005561813A

[li] Patent Number: 5,561,813 [45] Date of Patent: Oct. 1, 1996

5,317,093 5/1994 Cuenod et al 395/829

5,367,640 11/1994 Hamilton et al 395/275

5,402,528 3/1995 Christopher et al 395/109

5,410,717 4/1995 Floro 395/800

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5,434,562 7/1995 Reardon 340/825.34

OTHER PUBLICATIONS

Texas Instruments SN75C091A SCSI Bus Controller Data
Manual, Texas Instruments, Inc., 1990.
Biagioni, E. et al., "Designing a Practical ATM Lan" in IEEE
Network, vol. 7, No. 2 (Mar. 1993) pp. 32-39.

Primary Examiner—Lance Leonard Barry

Attorney, Agent, or Firm—Skjerven, Morrill, MacPherson,

Franklin & Friel; Alan H. MacPherson; David T. Millers

[57] ABSTRACT

An input/output port address selection circuit for a device that couples to a local bus of a computer operates in two modes. In a first mode, the I/O port address is maintained as the last I/O port address saved. In the second mode, the selection circuit changes the I/O port address and saves the change when the circuit is reset. A computer user resolves I/O port address conflicts by placing the selection circuit in the second mode then resetting the system until the conflict is resolved and the system works properly. The selection circuit is then placed and left in the first mode so that the non-conflicting address is reused. Non-volatile memory, an electrically erasable-programmable read-only memory, is used for saving an index which indicates the last I/O port address set. The non-volatile memory is changed when the selection circuit is operated in the second mode.

9 Claims, 4 Drawing Sheets